In a bowl, whisk together melted butter and brown sugar until smooth.
Add egg and vanilla extract.
In a separate bowl, combine flour, baking powder, salt, apple pie spice, and cinnamon.
Fold dry ingredients into wet ingredients until a dough forms.
Shape & Bake:
Scoop dough into muffin pan and press down in the center to make a cavity.
Bake for 22 minutes for large cups (12 for minis).
When done, press the center down again with a spoon or ice cream scoop—they’ll look soft, and that’s perfect!